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Ice Age/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, wakes up and looks out his frosty bedroom window. TIM: Cool! Hey! C’mon, Moby. Tim and a robot, Moby, step outside the front door to look at the ice and snow. TIM: Huh. Tim reads from a typed letter. TIM: Dear Tim and Moby, Are we in an ice age? From, Eric R. Tim and Moby stand outside in the snow. TIM: Well, yes and no. The term ice age can mean a couple of things. An image shows a map of the world. Animations show ice sheets and sliding glaciers. TIM: Scientifically speaking, it's any long period of time when the earth is covered with big slabs of ice called ice sheets and rivers of ice called glaciers. MOBY: Beep. An image shows glaciers on a sunny day. TIM: Oh, oh, really long, like tens or hundreds of millions of years. Technically, we are in an ice age, since we do have sheets of ice and glaciers on the Earth right now. You know, all that stuff in the North and South Poles. But the more common use of the term “ice age” refers to shorter periods when ice sheets cover lots of the earth. Scientists call these periods glaciations, and they're shorter than the other ice ages, they're only tens of thousands of years. An animation of the map of the world shows ice sheets moving over the North and South poles. TIM: During glaciations, ice sheets expand over the continents, and mountain glaciers expand. Between ice ages and glaciations, the earth warms up, sometimes a lot. About fiftyseven million years ago, the earth was so warm that the central United States looked like the tropics, trees grew in the North and South poles, and alligators lived in the Canadian Arctic Images set against a map of the world show tropical locations as they existed millions of years ago on Earth as Tim describes. An animation shows ice sheets in the Northern and Southern hemispheres growing and shrinking. TIM: About two and a half million years ago, the ice age that we’re currently in began. Ever since then, ice sheets have been expanding and shrinking pretty regularly every forty thousand to onehundred thousand years. The intervals of warmer years in between glaciations are called interglacial periods. That's what we're in now. MOBY: Beep. TIM: Well, the last glacial period ended about ten thousand years ago. So that's why people commonly say we're not in an ice age. An animation shows a large glacier moving toward a city skyline. TIM: If and when the next glacial period comes, ice sheets will expand again, but no one knows how far. MOBY: Beep. TIM: During the last glacial period, huge mammals roamed over lots of earth's continents. MOBY: Beep. TIM: Well, like the mastodon, the glyptodon, the giant sloth, the woolly mammoth, and sabertoothed cats. These are ancient types of megafauna, which means “really big animals.” Images show the five ancient mammals Tim names. MOBY: Beep. Images show a drilled sample of ice layers and the layers of the earth. TIM: Scientists learn about ice ages and glaciations in a few ways. Using special drills that can take core samples of ice sheets and study the layers of ice to see when they formed, like studying the layers of the earth. An image shows a fossil. TIM: They can also study the fossil record to see what kind of plants and animals lived where, and when. And they can study the surface of the Earth to figure out where slowmoving glaciers have changed the earth's surface. An animation shows a glacier sliding down a mountain. TIM: You know, glaciers have left their mark all over the United States. They've carved out the Great Lakes and Finger Lakes, sculpted Niagara Falls, and left behind a big pile of rocks in what we now call Long Island. Images show the places Tim describes. MOBY: Beep. TIM: Well, scientists aren't sure why ice ages begin and end, but there are probably a few factors responsible. An animation shows the earth in orbit. TIM: Changes in the earth's orbit can raise or lower the temperature of the planet. An animation shows the earth's land masses separating and moving away from each other. TIM: Movement of the tectonic plates can create or obstruct channels that carry warm water to different parts of the world. An animation shows a volcano's lava rising. TIM: Natural disasters like meteorites and volcanoes can have a huge impact on global climate. Tim and Moby built a lifesize Moby out of snow. It starts to melt quickly and Moby and Tim frown. MOBY: Beep. An animation shows the sun heating Earth’s. TIM: And changes in levels of carbon dioxide in the atmosphere can cause the earth to cool down, or warm up. MOBY: Beep. TIM: Well, levels of atmospheric carbon dioxide do go through natural cycles. And the lowest temperatures have tended to coincide with the lowest levels of carbon dioxide over the past 400 thousand years. But that's clearly changed in the last 100 years. See? CO2 levels are way above normal levels. A chart shows carbon dioxide levels rising dramatically over the last onehundred years while temperatures did not rise. An animation shows black smoke coming out of factory stacks and smoke coming out of cars' tailpipes. TIM: Most scientists agree that human activities like the burning of fossil fuels, which deposited huge amounts of CO2 into the atmosphere, have led to a major trend called global warming. MOBY: Beep. TIM: Actually, most scientists think that with global warming coming on so strong, it might be tens of thousands of years before we see another glaciation period where ice sheets cover the continents. MOBY: Beep. TIM: Yeah, I know. Well, what should we do? Moby's hand retreats and his arm blows snow all over Tim. Tim’s head and body are covered in snow. Category:BrainPOP Transcripts